Take a full year to pay for a Kindle Fire HDX today Amazon is making one last effort to sell more Kindle Fire HDX tablets this holiday shopping season by offering buyers an extended payment plan free of interest. The way it works is rather simple — you pay 25 percent of the retail cost at checkout, and the remaining balance is billed in three equal installments every 90 days. There are no finance charges, hidden fees, credit check, or application process to go through.